HELP! NO INJECTOR PULSE,...non running 96 suburban tried everything

[corbin dallas]

hello. i will try to give you overview,..need some help. my 96 suburban with stock vortec 5.7 crab injection. truck ran fine,..then started to skip and run rough especially after startup warm or cold. then smooth out after 1 mile. hard code of p01345 crank/cam correlation. also was running 28degrees timing and had misfire codes, mass air meter out of range, o2 sensor and lean codes. so rplaced mass air. no change, replaced distributor. double checked installation and made sure no slack in timing chain-no change. replaced crank sensor,..no change, replaced fuel punmp,..no change. then one day it sputtered and stumbled up the driveway and shut off. never ran again. checked injector pulse and nothing(not grounding),..got new computer and sent out to reprogram,..stil no run and no injector pulse. HELP!!!!!!!

 

[exp500]

Recheck engine grounds. Look in top of upper intake and see if 2 of the big oval gasket installed.
Unplug injector harness, test for power and ground on harness back to computer. A 194 bulb works good with alligator clip wire here. Computer is 5 volts. careful.

 

[Doubeleive]

did you test the icm (ignition control module)?

 

[corbin dallas]

Recheck engine grounds. Look in top of upper intake and see if 2 of the big oval gasket installed.
Unplug injector harness, test for power and ground on harness back to computer. A 194 bulb works good with alligator clip wire here. Computer is 5 volts. careful.

truck has multiple chassis and engine grounds(more than just the stock grounds,..but I will recheck). the upper and lower manifold gaskets are new and double checked. there is power at the plug to the injectors but NO grounding of the injectors(non of them) from the computer/harness. the computer is new and flashed for the suburban,..i also have the stock computer and same issue,..no injector ground so no pulse. checked with node light

 

[corbin dallas]

did you test the icm (ignition control module)?

I have not since I would suspect it would have noting to do with the harness to injectors not producing a ground to fire the injectors. am I wrong to assume that? i found a test procedure on her for icm,..but I think I have another one I can swap in and see. i will get back to you guys. thanks

 

[OR VietVet]

You said replaced distributor. What came with it? Module? Pickup coil? Cap? Rotor? Brand? Tested coil?

 

[exp500]

Ref post 4- Disconnect harness at both ends, check ground wire continuity. may be replacing a wire there.
Also test computer pin for ground when cranking. Hope you bought a factory service manual for pin /wiring layouts.
You will need a small connector like a butt splice for 22 gauge to get your meter connected to computer pins.
Lastly- Do you have a theft light flasing on dash? Does the light lite up when key on not started?

 

[corbin dallas]

You said replaced distributor. What came with it? Module? Pickup coil? Cap? Rotor? Brand? Tested coil?

yes new distributor. installed correctly. old distributor was probably fine as well since there is no shaft play,..but still no change. new cap rotor plugs wires.

 

[corbin dallas]

Ref post 4- Disconnect harness at both ends, check ground wire continuity. may be replacing a wire there.
Also test computer pin for ground when cranking. Hope you bought a factory service manual for pin /wiring layouts.
You will need a small connector like a butt splice for 22 gauge to get your meter connected to computer pins.
Lastly- Do you have a theft light flasing on dash? Does the light lite up when key on not started?

all harness wires look fine. trying to get a diagram to see what wires are for ground,..but can identify and chase each one from plug,..but all 8 have no ground pulse so doubt it is just one broken wire,..impossible for all 8 to just go bad. any ideas where to get pin diagrams? this is a 96. no anti theft at all

 

[Doubeleive]

I have not since I would suspect it would have noting to do with the harness to injectors not producing a ground to fire the injectors. am I wrong to assume that? i found a test procedure on her for icm,..but I think I have another one I can swap in and see. i will get back to you guys. thanks

I am not sure but the problems you described fit in with a bad icm

 

[exp500]

How many plugs on your computer/ECM? 5 correct? That is 96 only.

 

[corbin dallas]

I am not sure but the problems you described fit in with a bad icm

i replaced the ICM with a known good one,..NO change. still nop injector pulse at the injectors. so its not the ICM.

 

[corbin dallas]

How many plugs on your computer/ECM? 5 correct? That is 96 only.

yes 5. white black red blue and the small square one. 96-97 only

 

[Doubeleive]

i replaced the ICM with a known good one,..NO change. still nop injector pulse at the injectors. so its not the ICM.

it appears I wasn't too far off track, pulse comes from the ecm but icm also has something to do with, maybe check the injector harness and be sure you have a ground that has been a rare issue before on (gmt800's)
maybe this OLD thread on another forum may help?

No injector pulse?

www.gmtruckclub.com

 

[east302]

Pinout for a 1998 5.7L attached. Alldatadiy would have it, but they went up on their subscription cost so it’s not as much of a bargain as it once was. No guarantee that it’s the same for 96, but maybe close enough.

Did you set the CMP Retard (zero degrees at 1000-rpm) following the distributor replacement? That usually throws the P1345 code, but since you had it before I’d have said a distributor issue or timing chain problem.

Injector harness at intake:

 

[corbin dallas]

I have not since I would suspect it would have noting to do with the harness to injectors not producing a ground to fire the injectors. am I wrong to assume that? i found a test procedure on her for icm,..but I think I have another one I can swap in and see. i will get back to you guys. thanks

i tried a known good ICM and coil,..still no injector pulse.

 

[exp500]

A quick search showed downloadable pdf factory service manuals on ebay for $30 or so.
Search also found a few about 150 meg size free download. Suburban/tahoe/pickup will all work for this issue 96 only. 97 up computers 4 plug.
I still think you have some anti-theft, does it use a chipped key?

 

[corbin dallas]

A quick search showed downloadable pdf factory service manuals on ebay for $30 or so.
Search also found a few about 150 meg size free download. Suburban/tahoe/pickup will all work for this issue 96 only. 97 up computers 4 plug.
I still think you have some anti-theft, does it use a chipped key?

no chipped key. just old flat metal key. no antitheft warning light anywhere in gauge cluster. owned the truck for many years. no anti theft. not even a key fob. just single ignition key

 

[corbin dallas]

View attachment 353436View attachment 353434

View attachment 353435

Pinout for a 1998 5.7L attached. Alldatadiy would have it, but they went up on their subscription cost so it’s not as much of a bargain as it once was. No guarantee that it’s the same for 96, but maybe close enough.

Did you set the CMP Retard (zero degrees at 1000-rpm) following the distributor replacement? That usually throws the P1345 code, but since you had it before I’d have said a distributor issue or timing chain problem.

Injector harness at intake:


View attachment 353437

wow

View attachment 353436View attachment 353434

View attachment 353435

Pinout for a 1998 5.7L attached. Alldatadiy would have it, but they went up on their subscription cost so it’s not as much of a bargain as it once was. No guarantee that it’s the same for 96, but maybe close enough.

Did you set the CMP Retard (zero degrees at 1000-rpm) following the distributor replacement? That usually throws the P1345 code, but since you had it before I’d have said a distributor issue or timing chain problem.

Injector harness at intake:


View attachment 353437

well like I said it used to run even when i had the p01345 code. and the timing was crazy,..like 28 degrees. and got a new distributor to fix the problem,..and it didnt. i checked any play in timing chain and none at all,..it would start,..skip stumble and sputter right after startup and smooth out 100 feet down the road hot or cold. then one day it sputtered up the driveway and just dead. no injector pulse,....so if i can get it running again i will have to reset the distributor to zero,...i didnt do that when i installed the new one,..but it stopped running before i had the chance. thanks for the diagrams,...i will get back to you guys when i have more results!!! thanks

 

[exp500]

Check for spark, check for signal from crank sensor.